As I found it imperative to return to the United States in the interest of the expedition, I considered it expedient to reduce my scientific corps to three.  My camp at San Diego I left in charge of Mr. H. White, who later on was relieved by Mr. C. V. Hartman.  During my absence they conducted excavations of the mounds along the southern bank of the Piedras Verdes River, near its junction with San Miguel River, and in convenient neighbourhood to the camp.  Neither the mounds themselves nor the houses inside of them differ much from those already described on the upper part of the river, except that some of the mounds here were somewhat larger.  Judging from the beams left, they probably contained a few three-story houses.  However, in either locality most of the mound houses were only one story high, and where second or third stories were indicated, they were never found intact.  In neither place were circular houses observed.  The mounds here were located on a rich, alluvial clay soil.

Here, as on the upper part of the river, the treasures we secured were taken from underneath the floors of the houses, where they had been buried with the dead.  Here, as there, they consisted of beautifully decorated earthenware jars and bowls, some of them in bizarre representations of animal and human forms, besides stone implements, shell beads, pieces of pyrites and turquoise, all being generally unearthed intact.

The things were found alongside of skeletons, which were huddled together in groups of from two to five in one of the corners.  The jars, bowls, etc., had generally been deposited close to the body, as a rule near the head.  The skulls of the skeletons were mostly crushed, and crumbled to dust when exposed to the air.  There was no trace of charring on the bones, although in some cases charcoal was found close to the skeletons.

To excavate such mounds is slow and tedious work, requiring much patience.  Sometimes nothing was found for weeks.  Small mounds gave results as good as, if not better than, some large ones.  In shape they are more or less conical, flattened at the top; some are oblong, a few even rectangular.  The highest among them rose to twenty or twenty-five feet, but the majority varied from five to twelve feet.  The house walls inside of them were from eight to sixteen inches thick.

The pottery which was excavated here may be judged by the accompanying plates.  It is superior in quality, as well as in decoration, to that produced by the Pueblos of the Southwest of the United States.  The clay is fine in texture and has often a slight surface gloss, the result of mechanical polishing.  Though the designs in general remind one of those of the Southwestern Pueblos, as, for instance, the cloud terraces, scrolls, etc., still most of the decorations in question show more delicacy, taste, and feeling, and are richer in colouring.

This kind of pottery is known only from excavations in the valleys of San Diego and of Piedras Verdes River, as Well as from Casas Grandes Valley.  It forms a transition from the culture of the Pueblos of Arizona and New Mexico to that of the Valley of Mexico, a thousand miles farther south.  In a general way the several hundred specimens of the collection can be divided into four groups: